When running on a standard Microsoft Dynamics NAV or Microsoft Dynamics 365 Business Central license, you might have the issue that you cannot enable OData and you are not able to run the Web Service required by ForNAV, because you do not have permission to execute the page 7702 (Fields).
The error message is: “Could not reach Field WebService. You do not have the Execute permission on the Fields Page.”
To get around this, you must install the ForNAV Report Pack, because this includes an alternate page with the same functionality as page 7702. You should also make sure the ForNAV ISV granule (6188500 Reports ForNAV) is in the customer’s Microsoft Dynamics NAV/Dynamics 365 Business Central license.
You can read more about installing the ForNAV Report Pack here: https://www.fornav.com/knowledge-base/installing-standard-reports-in-fornav/
After installing the ForNAV Report Pack, in the ForNAV Setup window, on the Actions tab, click Create ForNAV WebService.